The present invention relates in general to emergency locking means for dual spool safety belt retractors employed in vehicles for restraining passengers in their seats during emergency conditions and more particularly to an improved dual locking pawl emergency locking means for such a retractor employing a single vehicle inertia sensor for operating the locking means.
Dual spool automatic locking safety belt retractors have been developed heretofore for use in automotive vehicles to automatically lock a pair of safety belts wound about the dual spools in an emergency condition encounted by the vehicle. In some instances the retractor is mounted between the vehicle seats with the seat belts serving two separate safety belt systems for the two front seat passengers. In other situations, the retractor may be used for storing two ends of safety belt webbing employed in a single harness arrangement for a single passenger to be restrained in the vehicle seat in the case of an emergency condition. It is common to sense such emergency conditions through the use of vehicle inertia sensors of known construction which react in response to vehicle acceleration or deceleration of more than a predetermined amount to activate locking means employed with the retractor.
Exemplary of prior art dual spool automatic locking retractors are U.S. Pat. Nos. 3,960,339; 3,974,979; 4,065,070; 4,135,683; and 4,164,336. In these prior art patents, a single pawl is provided between two spools of the retractor with the lockup of one end of the pawl with one spool causing the pawl to be moved into locking engagement with the other spool. The single pawls employed have been provided with a "floating" support as in U.S. Pat. No. 4,135,683 or a resilient mounting as in U.S. Pat. No. 3,960,339 in order to improve the locking characteristics of the single pawl employed between two spools.
Where a single double ended pawl is employed, as in the aforementioned prior art patents, there is the possibility that the pawl may experience a false latching condition if the pawl tooth ends, of either end, engage the tip of a tooth on the associated spool locking ratchet normally employed in locking retractor spools. We have therefore determined that there is a need for an improvement in the locking characteristics for an emergency locking means for a dual spool retractor employing a single inertia sensor for operation of the associated pawl means employed for locking the two spools.